Hepatitis B Virus(HBV) is a lethal virus which causes acute/chronic Hepatitis in human body, and finally developes the disease into liver cancer. At present, a remedy for treating the viral disease does not exist though vaccines against the virus have been developed. Up to the present, Ara-A, interferon or the like has been used in treatment of Hepatitis B, however, there are many problems in view of effectiveness and safety.
Recently, various nucleoside compounds having anti-HBV activity have been reported. For example, 2',3'-dideoxy-3'-thiacytidine[Proc. Natl. Acad. Sci. USA, 88, 8495 (1991)], 5-fluoro-2',3'-dideoxy-3'-thiacytidine[Proc. Natl. Acad. Sci. USA, 88, 8495(1991)], 2'3'-dideoxy-.beta.-L-5-fluoro-cytidine[Biochem. Pharm., 47, 171(1994)), 2',3'-dideoxy-.beta.-L-cytidine[Biochem. Pharm., 47, 171(1994)], etc. are reported as showing anti-HBV activity.
However, these compounds reported up to the present have substantial need to be improved in view of effectiveness and safety. Therefore, it is required to develop novel compounds having excellent effectiveness with low toxicity.